Field of the Disclosure
The present disclosure relates to a semiconductor technology, and in particular, it relates to a high-voltage semiconductor device that is capable of reducing or eliminating body effect.
Description of the Related Art
High-voltage semiconductor technology is applied to integrated circuits (ICs) with high voltage and high power. Traditional high-voltage semiconductor devices, such as lateral diffused MOSFETs (LDMOSFETs), are mainly used for devices with at least 18 volts or higher. The advantages of high-voltage device technology include cost effectiveness and process compatibility, and thus high-voltage device technology has been widely used in display driver IC devices, and power supply devices, and power management, communications, autotronics, and industrial control fields, etc.
FIG. 1 is a cross section of a conventional n-type LDMOSFET. The n-type LDMOSFET 10 includes a p-type semiconductor substrate 200 and a p-type epitaxial layer 102 thereon. A gate structure 116 and a field oxide layer 114 are on the p-type epitaxial layer 102. Moreover, a p-type body region 106 and an n-type drift region 104 are respectively in the p-type epitaxial layer 102 on both sides of the gate structure 116. The n-type drift region 104 further extends into the underlying p-type semiconductor substrate 200. A p-type contact region 108 and an adjacent n-type contact region 110 (or both referred to as a source region) are in the body region 106 and an n-type contact region 112 (or referred to as a drain region) is in the drift region 104. Moreover, a source electrode 117 is electrically connected to the p-type contact region 108 and the n-type contact region 110. A drain electrode 119 is electrically connected to the n-type contact region 112. A gate electrode 121 is electrically connected to the gate structure 116.
In such an n-type LDMOSFET 10, however, the source region is electrically connected to the underlying p-type semiconductor substrate 200 via the body region 106. Therefore, the body effect is induced to change the threshold voltage of the transistor 10 when the source region is coupled to an internal circuit or resistor. As a result, the driving current of the transistor 10 is reduced with increasing the voltage applied to the source region, and thus the performance of the transistor 10 is reduced.
Therefore, there is a need to develop a high-voltage semiconductor device and a method for manufacturing the same that are capable of addressing or mitigating the problems described above.